There have been various times in my life when I've felt "smart". Sometimes this goes along with some context in which others think I understand what is going on. When I realize that in some context I am considered "smart", my usual response is one of something of the sort: "wow, but I am so confused! I know so little!" Now, one might put this down as modesty, and say, no, in fact I know quite a bit and such and such. But to me this dynamic seems to expose something of the structure of knowledge in society (as I have encountered it). There are people who feel they are not so smart and that others have most things figured out, and there are those who realize they don't know very much, but somehow represent structured knowledge to the others. To me this feels like a hoax that doesn't serve either person very well.
Now, this is a caricature, and I wouldn't want to say that it says much about the actual validity of knowledge. I only point out that this is a dynamic that may complicate things when evaluating how much ground a particular area of study actually covers. Consider perhaps a set of different areas of study, each overlapping with the other in some way, and as a whole covering a large amount of ground. Suppose further that the people studying each area take the subject matter in the surrounding areas to be more solid than those actually studying them do themselves (though they may be less forthright about this aspect than they should be). How do we evaluate the total ground covered by the overlap of these different disciplines? I suppose, we need to try to gain a bit of expertise in each of the areas and ignore some of the sociology and build up our own picture of the total ground covered.